Apparatus for and method of tanning hides



M. M. MERRlTT May 8, 1928.

APPARATUS FOR AND METHOD OF TANNING HIDES Filed April 1, 1922 2 Sheets-Sheet 1 Die ((8 May 8, 1928. 1,668,652

r M. M. MERRITT I APPARATUS FOR AND METHOD OF TANNING fill DES Filed Ap ril l. 1922 2 Sheets-Sheet 2 Invehior:

Patented May 8, 1928.

UNITED STATES.

PATENT OFFICE.

MATTHEW u. mnamrmormnnnaron. MASSACHUSETTS, 'AssIeNon, 31 m SIGNMENTS, TO UNITED SHOE MACHINERY CORPQBATION, JERSEY, A CORPQRATIQN OF NEW JERSEY.

arraaarusron' AND METHOD or TAKN IN'G HID EB.

Application filed April 1;

This invention relates to the treating of hides and skins by'meansof liquids or by liquors containing chemical bodies for the purpose of producing either physical or 5 chemical changes, orboth. in the skins and hides undergoing treatment.

One of the chief difliculties heretofore encountered in .the tanning of skins or hides through the operation" of a machine or other apparatus, designed to reduce very considerably the amount of manual labor involved in the handling of the skins or-hides and to lessen even more markedly the timecone sumed in the tanning operations; has resided in the lack of uniformity in the results attained, not only in respect to'diflerent skins or hides but in respect to different portions of the same skin or hide. Ordinarily the amount of tanning liquor handled in the.

apparatus was very large with no adequate which case deterioration of the product would be relatively rapid.' In short, it has 7 heretofore been 'difiicult to maintain a high standard of excellence and-of uniformity in the quality of the product. v y

One of he ob 'ects of the present invention is to provide for a rapid circulation of" the treating liquor so that all partsof the skins or hidesin the apparatus may be uniformly bathed by the liquor which is itself maintained at uniform strength and ternperature throughout the whole body of the liquor due to the very rapidity of its circulation, It is a further object of the invention to provide an improved apparatus by which uniformity in the strength of the treating liquor may be readily obtained and in which the skins or hides may be subjected to uniform treatment by a relatively small body of treating liquor, the strength of submerged hides or skins.

The illustrated apparatus and several of 1922. Serial I mi. 548,801.

which may be readily changed from time to time according to operator.

the judgment of the According to applicant s method of tan ning skins 'or-hides the latter are alternately immersed in the treating liquorand- Withdrawn therefrom for suspension in the atmosphere of the treating chamber. the

hides or skinsbeing immersed in a relatively small body of treating liquor which is caused to flow by the hides or skins in a "ioleutly agitated stream to wash deposits of residue from thc freshly immersed hides or skins and to maintain uniformity in'the strength of the liquor and to cause it 'to reach all portions of the surfaces of the its important features, while especially adapted to the tanning of hides or skins,' may have other applications and uses, such,- for instance; as those which relate to washing, liming. or coloringoperations. As

shown. the vat in which the drum'revolves 1s relatively. small since it is designed to contain only a small body ofliquor which is in, constant circulation with the liquor in a small tank at ahigher level than the vat" and connected thereto by a relatively large pipe through which the liquor may' flow freely into the vat, thus creating a swiftly flowing stream oftreating liquor in the vat.

relatively small is of a size to contain all of the treating liquor used at anyone time in the apparatus so that the liquorwhile in the tank may receive additions to its strength in treating substances or diluted, as

may bedesired. In the illustrated construotion. the drum which carries the skins'or hides alternately into and out of the treat ing liquor in the vat is provided with an interior drum over which the hides or skins are lapped so that they are maintained in substantially extended condition as they are submerged in the violently agitated treating liquor, and released successively from closely overlapped relation to each other when adjacent to the tanning liquor, whereby all ortions of the skins or hides are insure of equal treatment in a treating liquor main- Preferably; and as shown, thetank'while tained, as nearly as possible of uniform strength.

Other features of the invention and other novel combinations of parts: will be described in the detailed specification and pointed out in the appended claims.

In the drawings, which show a preferred form of one embodiment of my invention:

Figure 1 is a plan view of a preferred form of apparatus for treating leather;

Fig. 2 is a side elevation thereof;

Fig. 3 is a vertical, longitudinal section through the apparatus shown in Fig. 1, being partly in elevation; and

Fig. 4 is a diagrammatic view showing a drum provided with an interior drum principally useful for supporting hides of relatively great length considering the diameter of the exterior drum.

Referring. to the drawings and to the preferred form of my invention selected for illustrative purposes, I.have shown an open drum 6 preferably provided with spaced supporting bars to constitute an open head at each end of the drum which is mounted on a shaft 7 with journal bearings 8, 8. The

. preferred form of drum illustrated is circumferentially provided with dowels 9 with open spaces therebetween. These dowels are removable so that the skins may be folded thereover or otherwise attached thereto prior to the application of the dowels to the drum. The skins may be held in place in any suitable way, but preferably by a strap or belt 10 (Fig. 1) surrounding the drum and bearing against the outer surfaces of the skins when they pass over the dowels.

In .Fig. 3 I have shown the skins hung in the drum. but I have purposely omitted many of the skins, as to illustrate them all would render the drawing confused and make less clear the action of the skins as the drum is revolved. Below the center of the drum, enclosing the lower portion thereof, I have provided a tank 11, preferably having its lower wall fitting relatively close to the outer periphery of the drum so that there will be but little of the material treating liquor which is not actively in contact with the drum and that portion of the contents thereof which is submerged. In the preferred form of my invention illustrated, the drum is immersed approximately onefourth of its total diameter in the treating liquor, the tank 11 being somewhat higher to prevent spillage.

In Fig. 4, I have shown the drum provided with an inner drum 22 which is important in treating certain classes of skins or hides, especially hides of considerable length. Thismay be used not only for thin and medium thickness hides, but also for sole leather, especially when the latter has been partially tanned. The operation of the inner drum is to permit the hides to wrap therearound, thereby minimizing that folding or crumpling thereof which is likely to result in a raised grain. While the hides or skins are lapped over each other on the inner drum so that they are maintained in substantially extended condition as they are being immersed in the violently agitated treating liquor, they are released from closely overlapped relation to each other when adjacent to the tanning liquor so that allsurfaces of the hides or skins may be reached by the liquor. \Vhere the inner drum is used, the depth of the liquor should be sufiicient to cover a portion thereof. The hides are preferably attached by the butts.

In connection with the tank 11, I have shown a supply tank 12 adapted to contain a relatively small volume of material treating liquor. The tank 12 is on a higher level than the tank 11, and is connected therewith by a gravity feed pipe 13 through which the liquor flows by gravity from the tank 12 into the tank 11 and also with a return connection 14 in which is interposed circulatory means exemplified by the centrifugal pump 15 for pumping liquor from the tank 11 into the tank 12. Where the open drum in which the skins are hung is adapted to contain about one hundred hides or skins of say fifteen square feet each, I have found that surprising results are attained by circulating the liquor at a rate approximating or exceeding two hundred gallons per minute. It is highly advantageous that'heating elements, exemplified by the steam pipes 16, be supplied, preferably in the side tank 12, so that the liquor may be kept at a uniform temperature. In tanning hides this temperature is preferably about 100 to 110 degrees Fahrenheit. The flow of liquor from the tank 12 to the tank 11 may be regulated by regulating therate of flow from the tank 11 to the tank 12. This may conveniently be done by providing the valve 17 in the pipe 14 between the centrifugal pump 15 and the tank 1.1. The pipe 13 is preferably so much larger than the pipe 14 that the level of the liquor in the two tanks 11 and 12 will be generally the Same, that in the tank 12 being only sufiiciently higher to cause rapid flow of the liquor through the pipe 13 back into the tank 11. To admit of emptying the tank 11, the connection of the pipe 14 is adjacent the bottom thereof, and a valve 20 is provided in the supply pipe 13. Thus, when the valve 20 is closed and the pump is continued in operation, the tank 11 will be very quickly emptied. The rapid circulation of a relatively small total volume of liquor, as described, results in a surging of the liquor past the materials being treated and, in the tanning of,hides, to which my invention is primarily though not exclusively directed, thissurging action not only provides almost absolutely uniform liquor throughout the entire supply thereof in use at any one time, but also speeds up the tanning operation by producing a superior penetration of the liquor into the hides. As the drum is revolved, in the drum shown in Fig. 3, the hides are subjected to a massaging action, falling upon and rubbing against one another. This is disadvantageous in treating many types of hides, and the type of drum provided with the inner drum'illustrated in Fig. t minimizes this action, greatly improving the leather, especially relatively large hides. For sole leather,'I have found that other methods of n'iounting the hides, as described in my application, Serial No. 588,606 filed Sept. 16, 1922 are preferable. The drum 18 may be revolved or driven in any suitable way, exemplified by the pulley 19 on the shaft 7. The rate of rotation of the drum may be varied somewhatfor different classes of work, but I" have found that,'where an-eightfoot drum is provided, the revolution thereof at oneto two It. P. -M. worksmost satisfactorily.

In the preferred form of my apparatusillustrated, the hides are immersed about one-quarter of the time and are out in the atmosphere about three-quarters of the time, more or less. While in the atmosphere,the hides are wet with the tanning or other liquor used and, the tanning operation continues, being in fact accelerated by theaction of the air on the hides when wet with the tanning liquor. In this connection, the evaporation of the water content of the tanning liquor while in the air is believed to ac celerate the action of the active material in the liquor on the hides. WVhere the liquor-is circulated at a very high rate, each hide asit is withdrawn from the liquor is coated with a film of liquor which is just-"as fresh as any other liquor in the. entire system,"

i this because all the liquor swirling and therefore that portion of the tanning'opera tion, while-the hide is out of the liquor and the water evaporates therefrom, is to a great extent hastened beyond the corresponding action which would take place if the liquor were not in very rapld circula-tion.""The' rate of evaporation ina properly designed system is very high, preferably amounting to at least one-twentieth of the entire volume of the liquor each twenty-four hours. This may or may not be compensated for oftener than every twenty-four hours, but I find that in tanning or re-tanning relatively light leathers, such as upper material, the whole operation may be completed in such a short time that it is necessary that tanning extracts or other materials be added progressively to increase the barkoinetertest of the liquor starting with a relatively low barkometer test liquor, say fifteen degrees for upper leather, followed by a very grzulualincrease and ending with a sudden increase to a liquor of relatively higlrbarkometertest, such, for mstance,as forty-five 'degrccs to eighty-live degrees barkometer depending on 'the hide. The water and chemicals may be added either separately or in combinationwith each other. It has been found that the addition of any large percentage of water to a tanning fiuid at any one time results 111 an nnperfect mixture so that'the leather being treated takes up the water and the absorption of the active tanning material is correspondinglyretarded; To this end, I preferthat the water be add 'cd to the tanning fluid at approximately the same rate that it is evaporated; This may be effected by i any other suitable way.

The swirling stream of tanning fluid, say

from two hundred to four hundred gallons per-minute In a tank containing say only eighteen inches of liquor at its point of greatest depth and fitting relatively closely to the wheel, results in a forcing of the liquor against'the surface of the submerged hides and consequently resultsin much greater penetration of the pores thereof than where a'still liquor is used, or where a.

hides when emerged because of evaporation of the inactii e water contentthereof. Y I

The use of my improved apparatus and method not only greatly lllClQilSOSlllB speed of tanning; but very. materially improvesthe" quality thereof, other factors such as the tanning solution and the hke being con- .stant. This in'ipro'ved quality-for any given tanning solution and quality of hide arises somewhat from the fact that'the hides are for a shorter time in contact with the water, which, as is well known, exerts a -dele-- n ordinary float valve 01min or loss with various foreign chemical ele-.

ments. The quality is also improved because. of the very nature of the action of the active tanning agents on the hide Where'impacted thereagainstbv swirling actionof the liquor and by the subsequent action of the film of liquor which is believed to g adually increase in strength'and which acts on the hides as the water is evaporated therefrom during the period of emergence.

By circiilating the liquor at an extremely rapid rate, I'am enabledto' maintain a substantially constant temperature throughout the entire volume thereof. Where the temperature is kept around 110 degrees Fahren heit, the liquor is of considerably less specific gravity than where colder and is con- ,stantially the same, considered in terms of percentage, at both high and low temperatures, but the liquor is considerably thinner at the higher temperature. resulting in easier penetration of the skin. The relatively uniform temperature of the liquor at say 110 degrees Fahrenheit renders generally uniform, barring great variations in humidity, the evaporation of the water from the hides when suspended in the air, and the residue, after acting strongly on the hide, tends to become gummy, this gummy substance, including both tans and nontans, being again washed from the hide by the swirling action of the bath when the hide is again immersed in the liquor at the bottom of the tank 11.,

thereby preventing that premature filling which would otherwise retard penetration andtan. During the filling operation. however, the tannage portion of the gummy material tends to fill the hide and the action of the swirling stream is to drive still further into the hide such elements of the relatively heavy liquor as contribute to filling.

It is highly desirable that the'operation of the filling of the hide with tanning material be deferred until the hide is tanned all the way through and the washing action of the rapidly swirling fluid, before referred to, to a large extent washes off the thickened tanning material on the hides as they return into the liquor. thus preventing premature filling. The filling is preferably deferred until after the hide is entirely tanned or practically entirely tanned, at which time the filling may be very readily and rapidly effected by an increase in the chemical content of the liquor so as to provide a barkometer of say from 25 to 85 degrees at 110 degrees Fahrenheit, depending on the thick ness of the leather used. This is a very importantfactor in improving the quality of the leather, because. if the leather is prematurely filled with thick and viscous tanning material, the tanning of the interior of the hide is only imperfectly efi'ected and is greatly retarded, with attendant stiffening of the grain side of the leather, causing brittleness and causing the leather to crack.

The supply tank 12 is particularly useful in that it permits the thorough admixture of tanning fluid and the introduction of additional water or of chemical bodies, avoiding at the same time both the disadvantages arising from contact of very weak liqnor on the hides, with the resultant absorption of water and retardation of the operation, coupled with injurious action on the when the hides are removed they may be.

relatively dry and clean. This also results in saving a great deal of the liquor, which may be used again.

Before starting the tanning operation, the grain may be struck by immersing the hide in av weak solution of tanning material, preferably while the hide is maintained relatively still, or, if desired, the grain may be struck in the apparatus illustrated by start- 7 ing with a very weak solution.

While I have shown and described a preferred form of one embodiment of my invention, it will be understood that changes involving omission, substitution, alteration and reversal of parts, and even changes in the mode of operation, may be made without departing from the scope of my invention, which is best defined in the following claims.

Claims:

1. The method of treating a hide or the like with tanning liquor which comprises alternately suspending the hide in the atmosphere while wet with the liquor for such length of time as to permit evaporation of a portion of the Water content of the liquor, thereby leaving on the hide a residue richer in tanning agents than the original liquor, and submerging the hide in a body of the liquor to wash off the residue and to wet the hide again with the liquor preparatory to repetition of the suspension in the atmosphere, and violently agitating said treating liquor by causing it to flow continuously past the hide at the rate of over gallons per minute while introducing the treating liquor at a point below the surface of the body of liquor near one end thereof and simultaneously withdrawing the treating liquor at a point near another end of the body of liquor.

2. The method of tanning a hide or the like which comprises suspending the hide from'the periphery of a rotatable drum with the hides hanging interiorly of the drum, rotating the drum relatively slowly and passing a violently agitated stream of hidetreating liquor past the bottom of said drum and through the lower portion thereof, whereby alternately to subject said hides to a partial drying in the atmosphere to leave a residue of lessened water content, and to wash off the residue and mix it with III the main bod of treating liquor while again wetting the hide with the treating liquor preparatory to emergence thereof as the drum is further rotated.

3. The method of tannin hides or the like which comprises subjecting them to the action of a rapidly circulated body of tanning liquor of relatively low barkometer test and relatively rapid penetrating capacity until substantlally tanned, and then subjecting them for a relatively short time to the action of a rapidl circulated body of tanning liquor of muci higher barkometer test and relatively slower penetrating capacity, thereby to avoid premature filling of the hide with resultant retardation of penetration and tanning at the interior of the hide while securing the desired filling of the hide after tanning is substantially or entirely completed.

4. The method of tanning heavy hides which comprises initially subjecting them while relatively still to the action of a grainsetting liquor and subsequently continuing the tanning operation b repeatedly and alternately sub'eeting the ides to the action of a rapidly fiowing stream of a tanning agent and to the action of the atmosphere.

5. Tanning apparatus comprising, in combination, amain tank for containin tannin liquor, a rotatable drum mounte over sai main tank and partially submerged in said main tank, an auxiliar tank of a capacity to contain all the liquor while the apparatus is in use, and circulating means for circulating the liquor rapidly through said main tank, the circulating means comprising a pump and a pipe for carrying the liquor from the main tank to the auxiliary tank and a much larger pipe to conduct the liquor in the reverse direction for causing a rapid flow of liquor through the main tank.

6. Tanning apparatus comprising, in combination, a rotatable drum partially submerged in tanning liquor, means for causing a rapidly flowing stream of liquor to pass through the drum, suspension means for hanging hides from the interior periphery of said drum, and supporting means in said drum for supporting the hides in extended overlapped relation as the drum is rotated to prevent undue folding or bending thereof while releasing said hides from closely overlapped relation generally successivelyadjacent to the tanning liquor;

In testimony whereof, I have signed my name to this specification.

MATTHEW M. MERRITT. 

